Taking an intuitive stab here, positive pressure from the gas in the bottle forcing some liquid around the edges of the cork? I've occasionally read that some authorities recommend storing bubblies upright, arguing that the inert gas in the headspace protects the wine anyway. This issue might add weight to that recommendation.

Hi Peter,From the picture it looks like a natural cork. It started off as a straight champagne cork possibly approximately 1- 1/8 inches in diameter and 1- 7/8 or 2 inches long and chamfered or beveled on both ends.

Question for Jeff- Does storing Champagne on their sides’ age “faster” than those standing up-right?

I believe Champagne corks, as well as some standard corks, are coated with a thin layer of of a food grade waxy silicone. My guess is that in compression and corking, this layer is damaged, thus allowing the wine to penetrate along the bottom surface of the cork. This area of the cork conforms to the internal shape and size of the bottle and becomes set there, while the rest of the cork, which is not exposed, maintains it's elasticity and expands outwards, trying to revert to it's original shape. I think the area about 1/4 inch above your highlight is wider than the internal diameter of the neck of the bottle.Edit: Whether there is a coating or not, I think it is still a function of the amount of penetration by the wine under pressure, and that's where the cork would lose it's elasticity over time.

Victorwine wrote:Hi Peter,From the picture it looks like a natural cork. It started off as a straight champagne cork possibly approximately 1- 1/8 inches in diameter and 1- 7/8 or 2 inches long and chamfered or beveled on both ends.

Hi Victor

It looks like a standard Champagne cork, agglomorate with two discs of solid cork at wine end, each 6-7mm thick.

I was looking for an unused cork I brought back from Champagne but can't find it, howvere I don't recall any chamfers on it, however a chamfer would account for the 'shrinkage' at the business end.

Peter May wrote:Going back to my idle query - isn't that the opposite of what is supposed to happen by keeping the cork wet?

For a normal cork, yes. However, Champagne corks are compressed significantly. Also, they are composite corks, with layers glued together with grains running at angle to each other, like plywood. I believe the glue (natural latex?) prevents (or hinders) the wine from migrating through the layers.

If using an automated corking machine (where the corks are placed in a hopper and automatically feed to the “iris”) I believe both ends of the corks are chamfered. As for agglomerated corks (if used with an automated corking machine) they would have cork discs at both ends. If doing it the “old fashion way” then it is a different story.

I discussed this issue with Lisa Airey, the Education Director for the French Wine Academy/French Wine Society (and if anyone is interested in getting a really sound and thorugh education in French wines, this is the place for you to go). She was formerly the Education Director and then the Director of the Society of Wine Educators. And she knows her stuff.

Lisa spoke to the reason for the champagne cork going from juponne (skirt shaped) to cheville (peg shaped) in the bottle:

Yes. The champagne cork changes from juponne to cheville because the cell structure of the cork (under pressure) begins to deteriorate over time, hence the 'drink within ten years' caveat.

As the cork becomes more peg-like, effervescence slowly escapes. Old bottles do not froth enthusiastically.

The condition of the cork is a good indicator as to how long a NV bottle has sat on the shelf!

Peter - the bottom of the cork has not shrunk. It has lost it's elasticity, apparently due to exposure to wine over time, as Hoke's reference suggests. The rest of the cork has retained more of it's elasticity and thus has tried to return to it's original shape.

Steve Slatcher wrote:I don't think it has exactly shrunk. The wet bit has just lost its elasticity a bit more than the rest of the cork.

Howie Hart wrote: amount of penetration by the wine under pressure, and that's where the cork would lose it's elasticity over time.

Going back to my idle query - isn't that the opposite of what is supposed to happen by keeping the cork wet?

I thought keeping the cork wet was keep the seal airtight - nothing specifically to do with elasticity. Whether this is true or not is another matter. I would have thought the inside of the bottle would always have conditions humid enough to prevent the cork drying to the point where it affected the seal.

I am also not sure it is the wetness that has caused the reduction in elasticity. Is there another cork layer change at about that point too? It is difficult to see in the image.

Corks “function” best when the humidity inside the cork it self is at 5 to 12 percent and when approximately 50 percent (or a little less) of their volume is air. The cork’s compression property is partly due to this “trapped air” and its elasticity property is partly due to the humidity inside the cork.

I think Robin has the right answer here--it's because of the positive pressure in the air space above the wine. Cork contains a lot of dead tree cells that are now just semi-rigid cellulose airbags--in a way, the structure of cork is a lot like bubble wrap. These cellulose airbags are at normal ambient air pressure. The positive pressure against the inner surface of the cork is going to crush some of these cells inward, permanently deflating them over time.